The present invention relates to a scarfing method and apparatus for cutting end portions of plate-like materials to form scarfed surfaces. More specifically, the present invention relates to a scarfing method and apparatus which, by using cutting tools such as circular saw, milling cutter and disc cutter, scarfs end portions of plate-like materials such as veneers, plywood, MDF and particle boards and particularly end portions of thin plate-like materials that are relatively likely to develop irregular deformations or undulations.
The irregular deformations or undulations refer generally to distortions, undulations and warps.
The applicant of the present invention has proposed, in Japanese Utility Model Laid-Open No. 7-26101, a veneer scarfing apparatus which scarfs a front or rear end portion of a veneer in a direction perpendicular to the direction of veneer fibers, which extend in a direction of veneer feed. This veneer scarfing apparatus performs the scarfing as follows. That is, rather than holding the front or rear end portion of the veneer with a pressing plate during the scarfing using a cutter, as has been done conventionally, the veneer scarfing apparatus provides a suction hole in a cutter receiving table instead of using the pressing plate, attracts the veneer to the suction hole by suction, corrects undulations of the veneer and then scarfs the veneer end portion by holding the cutting position immovable, thereby producing a cut or scarfed surface in good condition which has linear cutting lines.
The applicant of this invention has also proposed, in Japanese Patent Publication No. 7-45287, a veneer cutting apparatus that uses a pressing member which, when cutting a veneer with warps and undulations in a direction perpendicular to the direction of veneer feed by a rotating cutter disc, presses a veneer surface on at least a downstream or upstream side of the cutter disc with respect to the direction of veneer feed and at the same time moves together with the cutter disc, thereby cutting the veneer linearly with high precision.
With the technology proposed by the Japanese Utility Model Laid-Open No. 7-26101, because the veneer is held to the cutter receiving table by the suction hole formed in the cutter receiving table during scarfing, if there are cracks or gaps in a portion of the veneer to be cut, the holding action by suction is not performed effectively, leaving undulations of the veneer poorly corrected and thus failing to produce a scarfed surface in good condition whose front end is strictly linear.
Further, because it is structurally impossible to form the suction hole at a position very close to a point of contact with a cutting tool, a sufficient suction cannot be applied to the plate-like material up to its front end portion. Therefore, if there are undulations in a portion to be cut, the front end portion of the plate-like material cannot securely be held by suction even when there are no gaps in that portion. This may degrade the scarfed state of the front end portion of the veneer.
Another drawback of the conventional apparatus is that if the width of the suction hole and the width of the veneer are not equal, the side portions of the veneer cannot be held by suction. That is, if the width of the suction hole is larger than the width of the veneer and when the side portions of the veneer are attracted by suction, air is inevitably taken in, weakening the suction force and resulting in an insufficient holding of the veneer side portions.
Conversely, when the width of the suction hole is narrower than the width of the veneer, a problem arises that the side portions of the veneer naturally cannot be held by suction. Therefore, each time the width of the veneer changes, the width of the suction hole needs to be changed.
With the technology proposed by the Japanese Patent Publication No. 7-45287, a pressing member is employed which presses the surface of a veneer and at the same time moves together with a cutter disc. Although the pressed area of the veneer surface is near the cut surface, because the surface of that portion of the veneer which is to be cut away as a chip by the cutter disc is not pressed, it is not possible, when the veneer has undulations, to securely hold the veneer to the cutter receiving table during scarfing, thus failing to produce a cut surface in good condition.
In connection with the above-described problems, there are the following problems. Even when the preceding methods are used to flatten undulations of the veneer by suction or pressing and scarf the flat ends of the veneer, if the scarfed veneer is not sufficiently held immovable, a cutting tool may again contact and damage the scarfed surface. This phenomenon occurs when the cut surface that has been processed by so-called "front blades" is contacted by "rear blades."
Under these circumstances, it is an object of the present invention to provide a method and apparatus for scarfing an end portion of a plate-like material, which can produce a highly precise cut surface even when the plate-like material has undulations.
Another object of the present invention is to provide a method and apparatus which can prevent a scarfed surface from being damaged by the same cutting tool that has formed the scarfed surface, thereby maintaining a good scarfed surface.
Therefore, a method and apparatus for scarfing a plate-like material is characterized in that end portions of the plate-like material are cut to form scarfed surfaces by a rotary cutter, which linearly moves relative to the plate-like material, and by a cutter receiving table, with which blades of the rotary cutter are kept in contact and which receives and supports a pressing force from a pressing member; and that, on a downstream side of the rotary cutter with respect to the direction of a cutter linear movement relative to the plate-like material, the pressing member presses during the cutting operation at least a part of the surface of at least that portion of the plate-like material which is to be cut away as a chip from the plate-like material at a position near the blades of the rotary cutter, the surface of the plate-like material pressed by the pressing member being opposite the other surface held in contact with the cutter receiving table.
The method and apparatus for scarfing a plate-like material is also characterized in that, on an upstream side of the rotary cutter with respect to the direction of a cutter linear movement relative to the plate-like material, a cut surface engagement member is pressed against or set close to a scarfed surface near the blades of the rotary cutter while a cutting operation proceeds.